1. Field of the Invention
The present invention relates to an automatic clutch operating apparatus for performing the connection and disconnection of a friction clutch for an automotive transmission by an electronically-controlled motor-driven operation device through a hydraulic master cylinder and a hydraulic operating cylinder.
2. Prior Art
In a transmission of an automobile, it is known to utilize what is called an automatic hydraulic pressure generator, that is, a friction clutch is connected or disconnected by a hydraulic master cylinder operated by a computer-controlled motor. In such an automatic hydraulic pressure generator, an operation device for operating a hydraulic master cylinder by a motor is disclosed in DE-A No.4433824. In the constitution of the operation device, a worm is provided on an output shaft of the motor, and a piston rod of the hydraulic master cylinder is connected by a pin to a worm wheel meshing with the worm. According to such a constitution, rotation of the motor is reduced by the worm and the worm wheel and thereby torque is increased. Further, by utilizing the lever ratio due to the difference of the distance between the rotation center of the worm wheel and the connection point of the piston rod and the distance between the rotation center of the worm wheel and the meshing point of the worm and the worm wheel, the torque is increased and the rotary motion of the worm wheel is converted into the linear motion of the piston rod.
Also, the device is provided with a load accumulating means for quickly performing the disconnection of the clutch, in which means is utilized a compression spring device connected with the housinng at one end and with the worm wheel at the other end.
However, in order that the load may be accumulated and the accumulated load may work in the disconnecting direction of the piston rod in the operation device of DE-A No. 4433824, it is required that the mutual positional relation among the four points is strictly defined, namely the connecting point between the compression spring device and the housing, the connecting point between the device and the worm wheel, the rotation center of the worm wheel and the connecting point between worm wheel and the piston rod. As a result, the operation device has the weak points such that the design is very troublesome, the structure is complicated and the workability in assembling is inefficient, and the adjusting work is difficult.